The copending application identified above discloses a new and novel class of fire extinguishing compositions which can also be employed to advantage to flameproof cellulosic materials such as wood, paper, and cardboard. These novel compositions contain sodium chloride, magnesium chloride, sodium sulfate, calcium chloride, and magnesium sulfate in an aqueous carrier and, optionally, one or more of the following compounds: calcium sulfate, potassium sulfate, magnesium bromide, and potassium chloride.